X-rays are electromagnetic waves that are highly transmitted through objects and are frequently used for nondestructive, noncontact observation of internal structures of objects. Normally with an X-ray tube, X-rays are generated by making electrons, emitted from an electron gun, incident on a target. As described in Patent Document 1, with an X-ray tube, a tubular member (referred to hereinafter as an “electron gun housing unit”), housing an electron gun, is mounted onto a housing member (referred to hereinafter as a “target housing unit”) that houses a target. A tube axis of the target housing unit and a tube axis of the electron gun housing unit are orthogonal to each other, and the electrons, emitted from the electron gun, collide with the target and X-rays are generated from the target. The X-rays are transmitted through an X-ray emission window of the X-ray tube and irradiated onto a sample disposed at an exterior. The X-rays transmitted through the sample are captured by any of various X-ray imaging means.
Patent Document 1: U.S. Pat. No. 6,229,876